$E(t)$ models the daily amount of energy (in kilojoules, ${kJ}$ ) that a solar panel in Pago Pago generates, ${t}$ days after the autumn equinox. Here, $t$ is entered in radians.

${E}({t})=624 \sin (\frac{2 \pi}{365} {t})+8736$

What is the first day after the autumn equinox that the solar panel generates $8400 {~kJ}$ ?

Round your final answer to the nearest whole day.